Alkoxy-magnesium chlorides of general formula ROMgCl are employed for among other purposes preparing modified-support Ziegler-Natta catalysts, especially those based on titanium, for the polyolefin industry. They are superior to conventional Ziegler-Natta systems particularly because of their higher activity and higher stereospecificity in the polymerization of olefins.
The first potential educts that come to mind for preparing compounds of the ROMgX type are Grignard compounds of general formula RMgX in ether. This route, however, seems to be not generally accessible because of the problems involved in quantitatively removing the ether, which often disrupts polymerization. The literature describes many methods of preparing catalyst supports that include magnesium and a halide, especially chlorine. The first simple organometallic route to low melting-point products with or without hydrocarbon, however, is disclosed in European A 0 242 801, which describes preparing an alkyl-magnesium halide from magnesium and an alkyl halide in anhydrous hydrocarbons with oxygen compounds (alcohols, aldehydes, and ketones with 1 to 20 carbon atoms) in an inert-gas atmosphere at normal pressure and at a temperature of 40.degree. to 200 .degree. C. Preferred are alcohols with 1 to 18 carbon atoms. Treatment with .beta.-alkyl alkanols with 5 to 18 carbon atoms results in products that dissolve in hydrocarbons when 1.1 to 2.0 moles of alkanol are employed in terms of the magnesium. An essential characteristic of this process is that the reaction occurs in two steps. The Grignard compound is prepared in the first step and treated in the second step with the appropriate oxygen compound. When the alkyl halide and the alkanol were added simultaneously in just one step for comparison on the other hand (EPA 0 242 801, Examples A & B), the main products were magnesium dialkoxides.